<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script src="js/jquery-3.6.1.js"></script>
		<style type="text/css">
			.c {
				color: orange;
			}

			.fs {
				font-size: 30px;
			}

			.bc {
				background-color: orange;
			}
		</style>
	</head>
	<body>
		<div>博为峰</div>
		<button>切换</button>
		<script type="text/javascript">
			$('div').addClass('c');
			$('div').addClass('fs');

			$('div').removeClass('c');

			$('button').click(function() {
				$('body').toggleClass('bc');
			})
		</script>
	</body>
</html>
